A number of prior art compositions, both as disclosed in the literature and as sold commercially, contain minor amounts of solvents to improve stability and/or control viscosity. For example, U.S. Pat. Nos. 3,954,634 granted on May 4, 1976 to Monson et al. and 3,729,416 granted on Apr. 24, 1973 to Bruning et al, the latter mentioning alkanols, alkanediols, alkoxyalkane diols, and alkanones.
Katsumi et al, U.S. Pat. No. 3,850,818 issued Nov. 26, 1974 disclosed certain ethoxylated quaternary salts as fabric conditioning agents, admixed in specified proportions with conventional quaternaries and with one or more of the following additives: C.sub.1-3 alcohols, glycols, glycerol, sorbitol and urea. Katsumi's ethoxylated quaternaries have the structure ##STR1## where R.sub.1 is long chain alkyl; R.sub.2 is benzyl or an alkyl group having from 1 to 3 carbon atoms; the sum (m+n) is from 20 to 100; and X is Cl, Br or C.sub.2 H.sub.5 SO.sub.4. The Katsumi compositions were said to have good viscosity stability and freeze-thaw recovery.
Davis disclosed in U.S. Pat. No. 4,076,632 issued Feb. 28, 1978 a physically stable liquid fabric softening composition comprising cationic fabric softener, protonated di-polyethoxy monoalkyl amine, urea, and water. Among the U.S. Pat. No. 4,076,632 cationics were quaternary ammonium salts, quaternary imidazolinium salts, and mixtures thereof. Solvents such as alcohols, glycols and glycol ethers were used optionally.
In U.S. Pat. No. 4,157,307 issued June 5, 1979, Jaeger et al disclosed physically stable liquid fabric softener compositions containing, as softeners, specific mixtures of quaternary ammonium and quaternary imidazolinium cationics; as stabilizing agents, mixtures of protonated di-polyethoxy monoalkyl amine and lower alcohols defined broadly to include glycols and glycol ethers; and water; said compositions having a pH in the range between 3.5 and 5.5. The Jaeger et al compositions contained the softener mixtures for reasons of softening and antistat performance and economics, and the unusually low pH was said to be necessary to avoid a pH-incompatibility problem with the imidazolinium salts.
It has now been found that the protonated dipolyethoxy monoalkyl amine and lower alcohol disclosed by Jaeger et al to be an effective stabilizing mixture in specific situations is, surprizingly, an effective stabilizer in ordinary softener compositions containing noncyclic quaternary ammonium cationic softening agents. The stabilizer mixture of this invention comprises materials which are themselves chemically stable during prolonged periods of storage and warehousing, unlike those stabilizer mixtures of the prior art containing urea which introduce an inescapable risk of developing an odor problem caused by hydrolysis to ammonia and carbon dioxide under severe conditions of time, temperature and/or pH during storage. Thus a long felt need in the softener industry is satisfied.
In recent years, economic advantages have been shown for the use of various nonionic materials as fabric softeners when used in conjunction with cationic fabric softeners. Typical disclosures are Murphy et al, U.S. Pat. No. 4,085,052 issued Apr. 18, 1978; Barford et al, U.S. Pat. No. 4,128,484 issued Dec. 5, 1978; and Rudkin et al, U.S. Ser. No. 955,300 filed Nov. 27, 1978 which corresponds to European patent application 2085 laid open May 30, 1979. The amine/lower alcohol mixtures of the present invention have been found to impart physical stability also to mixed nonionic/cationic softening compositions.